The Shadows are the oldest of all the known races, including even thr Vorlons. This race was almost unknown to the entire galaxy until just several months ago, when the Shadows went on the move. During their attacks on members of the League of Non-Aligned Worlds, they would jump in, blow up everything in sight, and them jump back out. The Shadows have only been defeated several times, and only once when multiple Shadow ships are present.
The first two were due to the skill and leadership of Captain Sheridan, who, while under the command of the White Star, was able to destroy the Shadow ships by out-thinking them. The first time, he detonated a jumpgate as the Shadow ship came out of huperspace. The explosion was spectacular, resulting in the annihilation of the enemy vessel. The second occurance came when Sheridan lured a Shadow ship into the atmosphere of Jupiter where it was sucked into the gravity well and crushed to bits.
Another rare defeat that was handed to the Shadows was courtesy of a Vorlon fleet that engaged another comparable group of Shadow vessels. It was this battle that convinced all members of the League of Non-Aligned Worlds sign on with the Alliance of Light to fight the Shadows.
After the incident at Z'Ha'Dum, the Shadows have paused. But only one thing is for certain: when the Shadows do move, they'll hit their enemies twice as hard.
"Here is what he have been able to learn about the Shadows' technology."